The invention relates to a process for producing a printed circuit board with at least one conductor path applied as a metal layer on at least one electrically insulated surface of a substrate board, wherein the printed circuit board has connection areas for connection contacts. The invention also relates to a printed circuit board and uses therefor.
A measuring resistor for resistor thermometers is known from German Utility Model 80 03 431, which has a small ceramic board on which a thin resistance layer is applied. The lead-in wires necessary for electrical bonding are passed through borings of an insulating body and are melted onto the small ceramic board along with this resistance layer by means of a glass frit, whereby the resistance path is covered with a burned-in insulation layer of glass ceramic. The comparatively complex construction, which is hardly suited for a mass production of economical measuring resistors measuring resistors, proves to be problematic with the known arrangement.
Furthermore, from DE 30 02 112 A1, a paste with predetermined electrical conductivity is known in which an electrically non-conducting support material is provided with additives in order to attain a specified conductivity. Such a paste is used, for example, as a contact and solder mass for layer circuits in heating elements or sensors. It can be applied in usual processing procedures as, for example, screen printing.
In practice, such terminals applied in screen printing turn out to be suitable only for connection with thin wires and bonding wires or thin bands in a soft soldering process, owing to their slight layer thickness. When using standard connection wires, as are usual for cable connections, a poor mechanical fixation between connection wire or cable lead and the contact field on the substrate must be taken into consideration, from which a rapid separation can result, especially at elevated temperature or with mechanically high tensile stress. When using a thin bonding wire, this must then be lengthened further, from which difficulties can result in automated processes.